URLs support
SGBlog has simple regexp that can automatically create <a href>-s for
something that looks like URL. But it has hard coded possible schemes:
ftp://
gopher://
http://
https://
telnet://
Also if it sees something like
9a8e5797c8b2335a67868912900b742962083b6b
then it will recognize it as a commit's hash and create link to it.